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Archive - Oct 24, 2011

Rare Gene Mutation Associated with High Risk of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of severe visual loss among the elderly. Researchers had previously identified several relatively common genetic variants which together predict a person's increased risk for AMD, but a significant number of persons without the disease also have these variants. Now, for the first time, investigators have been able to clearly show a specific rare mutation called CFH R1210C that predicts a very high risk of AMD and is extremely uncommon among individuals who do not have the disease. Although it is a rare variant, accounting for about 1% of the total cases, it is highly related to familial disease and earlier age of onset. This research was published online on October 23, 2011 in Nature Genetics. The paper is a collaborative effort among investigators from Tufts Medical Center, Tufts University School of Medicine; Brigham and Women's Hospital; Massachusetts General Hospital; Duke University; and Johns Hopkins University. "Our paper shows that there is a genetic variant that confers high risk of the development of AMD; this finding not only clearly links CFH gene dysfunction to disease, but also might help to identify people who need to be screened more closely," said first author, Dr. Soumya Raychaudhuri, a researcher in the Divisions of Genetics and Rheumatology at Brigham and Women's Hospital and an Assistant Professor of Medicine at the Harvard Medical School. Prior to this publication, it was known that genetic variation within the CFH gene influenced risk of AMD in individuals. In the current study, researchers conducted sequencing and genotyping of CFH in 2,423 AMD cases and 1,122 controls in the laboratory of senior author Dr. Johanna M.

Nature Study Illuminates DNA Repar in Cancer Cells

An international team of scientists led by University of California (UC) Davis researchers has discovered that DNA repair in cancer cells is not a one-way street as previously believed. Their findings show instead that recombination, an important DNA repair process, has a self-correcting mechanism that allows DNA to make a virtual u-turn and start over. The study's findings, which appeared online on October 23, 2011 in Nature, not only contribute new understanding to the field of basic cancer biology, but also have important implications for potentially improving the efficacy of cancer treatments. "What we discovered is that the DNA repair pathway called recombination is able to reverse itself," said Dr. Wolf-Dietrich Heyer, UC Davis professor of microbiology and of molecular and cellular biology and co-leader of Molecular Oncology at the UC Davis Cancer Center. "That makes it a very robust process, allowing cancer cells to deal with DNA damage in many different ways. This repair mechanism may have something to do with why some cancer cells become resistant to radiation and chemotherapy treatments that work by inducing DNA damage." Dr. Heyer likens this self-correcting ability of the DNA repair system to driving in a modern city where u-turns and two-way streets make it easy to rectify a wrong turn. "How much harder would it be to re-trace your path if you were in a medieval Italian city with only one-way streets," he said. In the current study, Dr. Heyer and his colleagues used yeast as a model system to elucidate the mechanisms of DNA repair. They expect their findings, like most that come out of work on yeast, will be confirmed in humans. "Whether in yeast or humans, the pathways that repair DNA are the same," Dr. Heyer said. The research team used electron microscopy to observe repair proteins in action on strands of DNA.